Stepped Yeast Starter Calculator

[Steve@PMF82]

Not arguing! i don't claim to have more than 1/10th of the yeast knowledge/experience as wolfy. This is just my gist on the whole yeast calc thing, there may or may not be people with similar experiences.

For me Mr Malty led me to more repeatable techniques. Sure the numbers produced are ball park at best but it gave me something to aim for and has been the single biggest noticeable improvement to my beers.

With Sulli42's calculator i thinks its a massive step in the right direction, especially if your splitting packs of yeast.
Its all very well if you brew the same batch size every time and around the same gravity to go along the lines of 1-2L starter will be sufficient, over time you can see for yourself what works and what doesn't.

For me i brew very different types of beer one batch to the next and i would guess not nearly as frequent as a lot of people. Its usually in different volumes to account for gravity and my intended consumption of the style. So anywhere between 8 - 12L 1045 to 1075 wort. I've done three 23L batches 2 of those were for case swap.

If 6months or a year later i used the same technique that brought me decent results with my split yeast the first time when it was fresh, i can safely say that the resulting beer would not be nearly as good, as if i had of used the stepped starter calculator, especially if there is say 20 points gravity difference in the worts. It would have taken me much more trial and error over many years to work out how much yeast to pitch on different worts if these calculators were not available.

I guess my point is, just going by what has worked for me in the past blindly would produce a lesser quality beer than integrating the calculator into my regular yeast practice, in which i try to make the conditions i grow my yeast in the same every time.

Like everything else it depends heavily on how your mind works, the calculators give me targets to aim for each step of the way, whether or not those targets are met will never be known but at least i am using the same calculations every time i grow some yeast.

All this may sound like i take my yeast very seriously! But in reality i am fairly relaxed about the whole thing mostly because these calculators have given me consistent results i am happy with.

End morning coffee infused rant

 

[dustinsullivan]

I agree wholeheartedly with your statement, that without actually counting individual yeast cells, there is no way to know precisely how many cells are present in a given sample.

However, in the context of yeast propagation, most of the variables involved in cell growth are controllable; the quality of the wort, the inoculation rate of the starter, the amount oxygenation, and the temperature of the ferment, four very important factors affecting cell growth, are completely within the average home brewer’s control.

If one maintains a constant on these four variables, and then pitches an unknown quantity of yeast into a reasonably sized starter, after the initial fermentation, there will almost always be a measurable quantity of highly viable (+98%) yeast, if this yeast is then placed in an appropriate sized graduated cylinder and chilled for about 48 hours, one should end up with a nice compact, measurable volume of yeast. According to multiple reliable sources (i.e. Fix, Zainasheff et al.), this yeast cake should contain on average; around 3 billion cells per milliliter.

Is this method perfect? Not even close.

Is there a margin of error involved? No doubt.

But personally, I think its way less than +/- 50 to 100%, it’s probably closer to +/-25%.

I also agree with you that having repeatable and regular techniques to follow (and adjust as required) is very important; and Beer4U’s post above is a perfect example of that.

 

[Wolfy]

All this may sound like i take my yeast very seriously! But in reality i am fairly relaxed about the whole thing mostly because these calculators have given me consistent results i am happy with.

That's more-or-less what I was trying to say.
If your techniques and methods produce good beer and give repeatable results - that's the important thing - not what the exact yeast cell count is, or the margin of error.
Use a reliable and repeatable method (like this or other calculators) to give you an estimate of what is required, but then concentrate on yeast health (rather than being overly concerned about complicated mathematics and exact yeast cell counts).

 

[Steve@PMF82]

That's more-or-less what I was trying to say.
If your techniques and methods produce good beer and give repeatable results - that's the important thing - not what the exact yeast cell count is, or the margin of error.
Use a reliable and repeatable method (like this or other calculators) to give you an estimate of what is required, but then concentrate on yeast health (rather than being overly concerned about complicated mathematics and exact yeast cell counts).

:icon_chickcheers:

 

[donburke]

I agree wholeheartedly with your statement, that without actually counting individual yeast cells, there is no way to know precisely how many cells are present in a given sample.

However, in the context of yeast propagation, most of the variables involved in cell growth are controllable; the quality of the wort, the inoculation rate of the starter, the amount oxygenation, and the temperature of the ferment, four very important factors affecting cell growth, are completely within the average home brewers control.

If one maintains a constant on these four variables, and then pitches an unknown quantity of yeast into a reasonably sized starter, after the initial fermentation, there will almost always be a measurable quantity of highly viable (+98%) yeast, if this yeast is then placed in an appropriate sized graduated cylinder and chilled for about 48 hours, one should end up with a nice compact, measurable volume of yeast. According to multiple reliable sources (i.e. Fix, Zainasheff et al.), this yeast cake should contain on average; around 3 billion cells per milliliter.

Is this method perfect? Not even close.

Is there a margin of error involved? No doubt.

But personally, I think its way less than +/- 50 to 100%, its probably closer to +/-25%.

I also agree with you that having repeatable and regular techniques to follow (and adjust as required) is very important; and Beer4Us post above is a perfect example of that.

hi sulli,

have you changed your growth rate formulas on your calculator ?

i am getting what appears to be an abnormally larger number of new cells created,

e.g. 97 billion cells into a 1.5 litre starter intermittent shaking yields a total number of 415 billion cells at the end of that step

whilst i'd love it to be that easy, i'm certain it wasnt calculating such a high growth rate previously

 

[dustinsullivan]

hi sulli,

have you changed your growth rate formulas on your calculator ?

i am getting what appears to be an abnormally larger number of new cells created,

e.g. 97 billion cells into a 1.5 litre starter intermittent shaking yields a total number of 415 billion cells at the end of that step

whilst i'd love it to be that easy, i'm certain it wasnt calculating such a high growth rate previously

Thank you for bringing that to my attention don. I was making some modifications to the app last night, and apparently changed some parameters that should not have been changed.
I've repaired the damage, should be back to normal. Thanks again.

 

[DJ_L3ThAL]

Fantastic thread (sorry to dig it back up!), has helped me in my understanding to create my first starter, to outline my rationale:

1. Used MrMalty to calculate my yeast slurry sample viability (is 10% based on being ~2 months old in fridge).
2. Used "rule of thumb" that there are 1.2 billion cells per mL of slurry, so at 10% viability if I used 2x 20mL slurry samples I am starting with 4.8 billion cells.
3. Used sulli's calculator for the beer I'm brewing and came up with 3 steps, sample into 300mL into 500mL into 800mL (so final starter volume 1.6L) will give me the required 178 billion cells to chill, decant and pitch the slurry into the fermenter once ready.

Thanks again, looking forward to tasting my 2nd All-Grain Dr.Smurto's Golden Ale using re-harvested US-05 :beer: :beer: :beer:

 

[syl]

Just thought I'd pop in and say yeastcalc.com for stepped starters is amazing!